Production method for multilayer substrate with piezoelectric film

Abstract

[Problem] To provide a production method for a multilayer substrate with a piezoelectric film capable of efficiently forming a piezoelectric film on a target substrate while ensuring the quality of piezoelectric performance and the like. [Solution] A production mechanism A has a box-type acrylic box 1. A conveyance unit 2, a spray application unit 3, a drying and cooling unit 4, and a firing unit 5 are provided inside the acrylic box 1. The production mechanism A has a low-humidity gas supply unit, and is capable of controlling the humidity of the internal environment of the acrylic box 1 by supplying dry air to the inside of the acrylic box 1. The low-humidity gas supply unit is capable of controlling the humidity of the internal environment of the spray application unit 3. Furthermore, a firing furnace 50 constituting the firing unit 5 has a temperature and humidity control device, and is configured to be capable of controlling the in-furnace temperature and humidity to be fixed values during the firing of the substrate inside the firing furnace 50.

Description

Method for manufacturing a laminated substrate with a piezoelectric film

[0001] The present invention relates to a method for manufacturing a laminated substrate with a piezoelectric film.

[0002] In recent years, laminated substrates with piezoelectric films have been widely used in various applications such as ultrasonic sensors and probes for medical echographs.

[0003] In this laminated substrate with a piezoelectric film, the piezoelectric film formed on the substrate has a piezoelectric effect that converts electrical energy and mechanical energy. For example, by applying an alternating voltage, a vibrator can generate ultrasonic waves.

[0004] As one method for manufacturing a laminated substrate with a piezoelectric film, a piezoelectric material solution composed of a composite of a piezoelectric sol-gel solution and piezoelectric powder is spray-coated on the surface of the substrate, and this is fired to form a coating film that becomes a piezoelectric film. A method has been proposed (see, for example, Patent Document 1).

[0005] Here, in the method for manufacturing a laminated substrate with a piezoelectric film described in Patent Document 1, the piezoelectric material solution contains powder, and by spray-coating this, a porous coating film is formed after firing, and a piezoelectric film that is flexible and resistant to thermal shock can be formed.

[0006] Further, the manufacturing method of spray-coating such a piezoelectric sol-gel solution is easier to form a thin film with a thickness of about several μm compared to the manufacturing method of dicing a bulk material to a desired film thickness (bulk method), and has the advantage that variations in film thickness and the like that are affected by dicing are unlikely to occur.

[0007] Japanese Patent No. 6829851

[0008] However, in the method for manufacturing a laminated substrate with a piezoelectric film described in Patent Document 1, there is a problem that the yield is low, such as the quality of the coating film and the piezoelectric performance of the substrate after manufacturing become insufficient due to peeling of a part of the formed thin film. Further, the peeling of the thin film occurs not only in the manufacturing method of spray-coating but also in other manufacturing methods.

[0009] And when a part of the formed piezoelectric film (thin film) peels off, ultrasonic waves cannot be transmitted and received, and the desired function cannot be imparted to the substrate.

[0010] Furthermore, when wiring the piezoelectric film after deposition so that it can be used as a probe, an anisotropic conductive adhesive is used to attach an FPC (Flexible Printed Circuit) to the upper electrode placed above the piezoelectric film. However, the elasticity of the FPC sometimes caused the piezoelectric film to peel off.

[0011] This invention was conceived in view of the above points, and aims to provide a method for manufacturing a piezoelectric film-coated laminated substrate that can efficiently form a piezoelectric film on a target substrate while ensuring quality such as piezoelectric performance.

[0012] To achieve the above objective, the present invention provides a method for manufacturing a piezoelectric laminated substrate, comprising: forming a piezoelectric film on a substrate using a piezoelectric material solution containing a composite of a sol-gel solution and a powder; a coating step of spray-applying the piezoelectric material solution to the substrate under a first atmosphere in order to substantially fill at least one of the recesses on the substrate surface, or recesses on the surface of the coating film that will become the piezoelectric film laminated on the substrate, or gaps in the coating film, or pores in the coating film with the piezoelectric material solution; a heat treatment step of heat-treating the spray-coated substrate under a second atmosphere; and a transport step of transporting the substrate between the coating step and the heat treatment step via a transport unit that transports the substrate under the first atmosphere and the second atmosphere, wherein the relative humidity of the first atmosphere and the second atmosphere is controlled to be below a predetermined value, and the coating step and the heat treatment step are performed multiple times to laminate the coating film onto the substrate.

[0013] In this process, by spray-coating a piezoelectric material solution containing a composite of a sol-gel solution and powder onto the substrate, a porous, flexible, and thermally shock-resistant piezoelectric film can be formed. Furthermore, compared to piezoelectric material solutions that do not contain powder, the film thickness formed in a single treatment is increased, improving the efficiency of film formation.

[0014] Furthermore, the coating process involves applying the piezoelectric material solution to the substrate under a first atmosphere controlled to have a relative humidity below a predetermined value. This reduces the influence of ambient humidity during spray coating, resulting in a coating film that is free from unevenness and cracking and exhibits good piezoelectric performance. Additionally, moisture that would otherwise prevent the piezoelectric material solution from filling at least one of the following—the recesses on the substrate surface, the recesses on the coating film surface that form the piezoelectric film laminated on the substrate, the gaps in the coating film, or the pores in the coating film—is reduced, allowing the piezoelectric material solution to substantially fill the recesses on the substrate surface, etc. Moreover, when the coating film is formed, the occurrence of recesses on the substrate surface, recesses on the coating film surface, gaps in the coating film, or pores in the coating film, which would serve as starting points for peeling, becomes less likely, resulting in a good coating film that is less prone to peeling.

[0015] It should be noted that "substantially satisfying" as used herein does not mean, for example, that all depressions on the substrate surface are filled with the piezoelectric material solution, but rather that the piezoelectric material solution is filled to the extent that peeling of the coating film is suppressed. Furthermore, "substantially satisfying" as used herein means filling depressions, gaps, or pores in the coating film surface formed by the first spray application of the piezoelectric material solution onto the substrate, and filling depressions, gaps, or pores in the coating film surface formed by subsequent spray applications, and also includes filling depressions, gaps, or pores in the coating film surface found in the coating film formed earlier (for example, the coating film formed by the first spray application) during the second and subsequent spray application processes. The same applies to the notation "substantially satisfying" as used below.

[0016] Furthermore, controlling the relative humidity to be below a predetermined value means that the amount of moisture (water vapor) per unit volume in the air is controlled to be below a predetermined value. For example, this includes reducing the amount of moisture in the air by dehumidifying in the same temperature environment, or by lowering the temperature in the same space.

[0017] Furthermore, the heat treatment process involves heat-treating the spray-coated substrate in a second atmosphere where the relative humidity is controlled to be below a predetermined value. This reduces the influence of ambient humidity during heat treatment, enabling the formation of a coating film that is free from unevenness and cracking and exhibits good piezoelectric performance. Additionally, the heat treatment process reduces moisture that would otherwise hinder the filling of recesses on the substrate surface, recesses on the coating film surface that form the piezoelectric film laminated on the substrate, gaps in the coating film, or pores in the coating film with the piezoelectric material solution. This allows the recesses on the substrate surface to be substantially filled with the piezoelectric material solution.

[0018] Furthermore, in the transport process, by transporting the substrate between the coating process and the heat treatment process via a transport unit that transports the substrate under a first atmosphere and a second atmosphere, the substrate with the piezoelectric material solution spray-coated can be moved in a humidity-controlled environment. This also reduces the influence of ambient humidity on the solution before it hardens on the substrate, making it easier to form a good coating film. In addition, during the transport process, moisture that would otherwise prevent the piezoelectric material solution from filling recesses on the substrate surface, recesses on the coating film surface that will become the piezoelectric film laminated on the substrate, gaps in the coating film, or pores in the coating film is reduced, allowing the piezoelectric material solution to substantially fill recesses on the substrate surface.

[0019] Furthermore, by performing the coating and firing processes multiple times and accumulating the coating films that will become piezoelectric films on the substrate, a piezoelectric film of a desired thickness can be provided on the substrate.

[0020] Furthermore, if the heat treatment process includes a firing process for firing the spray-coated substrate, the piezoelectric material solution applied to the substrate or coating can be fired and solidified into a coating film in a second atmosphere, thereby substantially filling any depressions on the substrate surface with the piezoelectric material solution.

[0021] Furthermore, if the heat treatment process includes a drying process for drying the spray-coated substrate, the spray-coated piezoelectric material solution can be made to blend with the substrate or the baked coating film of the underlying layer, thereby forming an even better coating film. Additionally, this process can be carried out under a second atmosphere, allowing the piezoelectric material solution to substantially fill any depressions on the substrate surface.

[0022] Furthermore, if the heat treatment process includes a cooling step to cool the fired substrate before the next coating step, it is possible to suppress the evaporation of the piezoelectric material solution that will become the next coating film due to the heat generated during firing in the coating film formed on the substrate when spray-coating the piezoelectric material solution that will become the next coating film. In addition, it is possible to form a good coating film that is difficult to peel off.

[0023] Furthermore, if the process includes a coating fixing step in which multiple coating films laminated on a substrate are fixed to the substrate using an insulating polymer adhesive, the peeling of the multiple coating films that form the piezoelectric body can be further suppressed. In addition, the adhesive strength of the polymer adhesive adheres the multiple coating films to the substrate or the lower coating film, making peeling less likely even when external forces are applied. Moreover, because the polymer adhesive is insulating, it can block electrical contact between the piezoelectric body film and the FPC (Flexible Printed Circuit) attached during wiring when the piezoelectric body film is used as a probe, and between the FPC and the substrate that serves as the lower electrode.

[0024] Furthermore, if the coating process includes a vibration step in which the substrate is vibrated after spray coating the piezoelectric material solution, the piezoelectric material solution can more easily penetrate into depressions on the substrate surface, depressions on the surface of the coating film that forms the piezoelectric body film laminated on the substrate, gaps in the coating film, or pores in the coating film, making it even easier to fill the depressions on the substrate surface with the piezoelectric material solution. In addition, it becomes possible to form a coating film that is even more resistant to peeling.

[0025] Furthermore, if the coating process includes an inspection step to inspect the substrate or the coating film laminated on the substrate before and after spray-coating the piezoelectric material solution, the surface shape of the coating film can be determined through inspection. For example, if recesses or other imperfections are found and the product does not meet certain standards, the piezoelectric material solution can be spray-coated again to ensure the quality of the coating film.

[0026] Furthermore, if the first and second atmospheres are controlled to have a relative humidity of 40% or less, it becomes possible to sufficiently reduce the influence of ambient humidity and form a coating film that is free from unevenness and cracking and has good piezoelectric properties.

[0027] Furthermore, if the first and second atmospheres are controlled to have a relative humidity of 20% or less, it becomes possible to more effectively reduce the influence of ambient humidity and form a coating film that is free from unevenness and cracking and has good piezoelectric properties.

[0028] Furthermore, if the transport unit consists of at least one of the following: a robotic arm capable of gripping substrates, a belt conveyor, an AGV (Auto Guided Vehicle), or an AMR (Autonomous Mobile Robot), control instructions can be given to the robotic arm, etc., to automate the operation of transporting the substrates.

[0029] Furthermore, the piezoelectric constant d of the piezoelectric film ３３ When the coefficient of capacitance is 50 pC / N or higher, a laminated substrate with a piezoelectric film that has sufficiently good piezoelectric performance can be obtained.

[0030] Furthermore, in order to achieve the above objective, the present invention provides a method for manufacturing a piezoelectric laminated substrate, comprising: a basic step of applying or adhering the piezoelectric material solution to the substrate in order to substantially fill at least one of the recesses on the substrate surface, or the recesses on the surface of the coating film which will become the piezoelectric laminated on the substrate, or the gaps in the coating film, or the pores in the coating film with the piezoelectric material solution; and the basic step The process includes a heat treatment step for heat-treating the substrate and a transport step for transporting the substrate between the base step and the heat treatment step via a transport unit, the base step and the heat treatment step are performed multiple times, the coating film is laminated onto the substrate, and predetermined properties are formed such that there are differences between the substrate and the first layer of coating film on the substrate, and / or between at least one pair of n-th layer and n+1-th layer of coating film among the laminated coating films, and at least one of the laminated coating films is applied to the substrate by spray coating in the base step.

[0031] In this basic process, a piezoelectric material solution containing a composite of a sol-gel solution and powder can be applied to or attached to the substrate, thereby forming a piezoelectric coating on the substrate.

[0032] Furthermore, by performing the basic and firing processes multiple times and laminating the piezoelectric coating onto the substrate, a piezoelectric film of a desired thickness can be provided on the substrate. The term "coating" here is not limited to coatings formed by spray coating, but also includes coatings formed by methods other than spray coating. Examples of methods other than spray coating include spin coating, roll coating, or sputtering.

[0033] Furthermore, by ensuring that the substrate and the first layer of coating on the substrate have different properties, it becomes easier to improve the adhesion between the substrate and the first layer of coating on the substrate, thereby preventing the coating, which forms the piezoelectric film, from peeling off.

[0034] Furthermore, by ensuring that at least one pair of the nth layer and the (n+1)th layer of the laminated coating films have different properties, it becomes easier to improve the adhesion between the nth layer and the (n+1)th layer, thereby preventing the peeling of the multiple coating films that form the piezoelectric film.

[0035] Furthermore, by applying a piezoelectric material solution to the substrate by spray coating in the basic process as one of the layered coating films, the piezoelectric film can be made porous, flexible, and resistant to thermal shock. In addition, compared to piezoelectric material solutions that do not contain powder, the film thickness formed in a single process can be increased, improving the efficiency of coating film formation.

[0036] Furthermore, if the predetermined property is the film thickness, the film thickness of the first coating layer on the substrate can be adjusted to improve the adhesion of the first coating layer to the substrate surface, thereby further suppressing the peeling of the coating layer that forms the piezoelectric film from the substrate. In addition, by making the film thickness of the nth coating layer and the (n+1)th coating layer different, the adhesion between the two layers can be improved, further suppressing the peeling of multiple coating layers that form the piezoelectric film.

[0037] Furthermore, if the predetermined property is the particle size of the powder before it is mixed with the sol-gel solution to form a composite, the particle size of the powder before it forms the first layer of coating on the substrate can be adjusted to change the density and porosity of the coating, thereby improving the adhesion of the first layer of coating to the substrate surface and further suppressing the peeling of the coating that will become the piezoelectric film from the substrate. In addition, by making the particle size of the powder before it forms a composite different for the nth layer and the (n+1)th layer of coating, the density and porosity of each coating can be changed to improve the adhesion between the two layers and further suppressing the peeling of multiple coatings that will become the piezoelectric film. Note that the particle size of the powder referred to here means the average particle size of the diameter of the powder before it is mixed with the sol-gel solution to form a composite.

[0038] Furthermore, if the predetermined property is the mixing ratio of the sol-gel solution and powder in the composite, the mixing ratio of the sol-gel solution and powder constituting the first layer of coating on the substrate can be adjusted to change the density and water activity of the coating, thereby improving the adhesion of the first layer of coating to the substrate surface and further suppressing the peeling of the coating that forms the piezoelectric film from the substrate. In addition, by making the mixing ratio of the sol-gel solution and powder different for the nth layer and the (n+1)th layer of coating, the density and water activity of each coating can be changed to improve the adhesion between the two layers and further suppress the peeling of multiple coatings that form the piezoelectric film. Note that the mixing ratio referred to here also includes cases where one of the nth layer or the (n+1)th layer of coating contains both sol-gel solution and powder, and the other has a mixing ratio of "sol-gel solution:powder = 0:100".

[0039] Furthermore, if the predetermined property is viscosity, the viscosity of the first coating layer on the substrate can be adjusted to improve the adhesion of the first coating layer to the substrate surface, thereby further suppressing the peeling of the coating layer that forms the piezoelectric film from the substrate. In addition, by laminating materials with different viscosities for the nth and n+1th layers of coating, the adhesion between the two layers can be improved, further suppressing the peeling of multiple coating layers that form the piezoelectric film.

[0040] Also, in the case where, in the base process, after applying or adhering a piezoelectric material solution to a substrate, a vibration process for vibrating the substrate is provided, the piezoelectric material solution easily penetrates into recesses on the substrate surface, recesses on the surface of the coating film that will become the piezoelectric body film laminated on the substrate, gaps between the coating films, holes in the coating film, etc., and furthermore, it becomes easier to fill the recesses on the substrate surface, etc. with the piezoelectric material solution. Also, it becomes possible to form a better coating film that is more difficult to peel off.

[0041] When the base process is performed in a first atmosphere and the first atmosphere is controlled so that the relative humidity is below a predetermined value, the influence of the humidity in the environment during the process is reduced, and a coating film without unevenness or cracks and having good piezoelectric performance can be formed. Also, moisture that prevents at least one of the recesses on the substrate surface, recesses on the surface of the coating film that will become the piezoelectric body film laminated on the substrate, gaps between the coating films, and holes in the coating film from being filled with the piezoelectric material solution is reduced, and the recesses on the substrate surface, etc. can be substantially filled with the piezoelectric material solution. Also, when forming the coating film, recesses on the substrate surface, recesses on the coating film surface, gaps between the coating films, holes in the coating film, etc. that serve as starting points for peeling are less likely to occur, and a better coating film that is more difficult to peel off can be formed.

[0042] Here, "substantially filled" does not mean, for example, that the piezoelectric material solution fills all the recesses on the substrate surface, etc., but includes that the piezoelectric material solution fills the recesses on the substrate surface, etc. to such an extent that peeling of the coating film can be suppressed. Also, here, "substantially filled" means filling the recesses on the surface of the so-called first coating film, gaps between the coating films, holes in the coating film, etc. that are formed by first applying or adhering the piezoelectric material solution on the substrate, and in addition to filling the recesses on the surface of the coating film, gaps between the coating films, holes in the coating film, etc. that are formed by applying or adhering in the second and subsequent times, further filling the recesses on the surface of the coating film, gaps between the coating films, holes in the coating film, etc. found in the coating film formed earlier (for example, the coating film formed in the first treatment) during the process of applying or adhering in the second and subsequent times. The same applies to the notation "substantially filled" that appears below.

[0043] Also, the control such that the relative humidity here becomes a predetermined value or less means that the moisture (amount of water vapor) per unit volume in the air is controlled to be a predetermined value or less. For example, it includes reducing the moisture amount in the air by dehumidifying in the same temperature environment or reducing the temperature in the same space to reduce the moisture amount in the air.

[0044] Further, in the heat treatment step, when the treatment is performed in the second atmosphere and the second atmosphere is controlled such that the relative humidity becomes a predetermined value or less, the influence of the humidity in the environment during heat treatment can be reduced, and a coating film without unevenness or cracks and having good piezoelectric performance can be formed. Also, even in the heat treatment step, moisture that prevents the recesses on the substrate surface, the recesses on the coating film surface that will become the piezoelectric film laminated on the substrate, the gaps between the coating films, or the holes in the coating film, etc. from being filled with the piezoelectric material solution is reduced, and the recesses on the substrate surface, etc. can be substantially filled with the piezoelectric material solution.

[0045] Further, in the transfer step, when the substrate is transferred in the first atmosphere and the second atmosphere and the first atmosphere and the second atmosphere are controlled such that the relative humidity becomes a predetermined value or less, the substrate in a state where the piezoelectric material solution is applied or adhered can be moved in an environment where the humidity is controlled. Also, the influence of the humidity in the environment on the solution before it solidifies on the substrate is reduced, making it easier to form a good coating film. Also, even in the transfer step, moisture that prevents the recesses on the substrate surface, the recesses on the coating film surface that will become the piezoelectric film laminated on the substrate, the gaps between the coating films, or the holes in the coating film, etc. from being filled with the piezoelectric material solution is reduced, and the recesses on the substrate surface, etc. can be substantially filled with the piezoelectric material solution.

[0046] Also, when the first atmosphere and the second atmosphere are controlled such that the relative humidity becomes 40% or less, it is possible to sufficiently reduce the influence of the humidity in the environment and form a coating film without unevenness or cracks and having good piezoelectric performance.

[0047] Furthermore, if the heat treatment process includes a drying process for drying the substrate, the piezoelectric material solution on the substrate can be made to blend with the substrate or the fired coating film of the underlying layer, thereby forming an even better coating film. Additionally, by performing this process under a second atmosphere, recesses and other defects on the substrate surface can be substantially filled with the piezoelectric material solution.

[0048] Furthermore, if the heat treatment process includes a cooling process to cool the fired substrate, it is possible to prevent the piezoelectric material solution that will form the next coating from evaporating due to the heat generated during firing in the coating formed on the substrate when applying or attaching the piezoelectric material solution that will form the next coating. In addition, it is possible to form a good coating that is difficult to peel off.

[0049] Furthermore, if an inspection process is included for inspecting the substrate or the coating film laminated on the substrate, the surface shape of the coating film can be determined through inspection, and if, for example, recesses are found and certain standards are not met, the piezoelectric material solution can be applied or adhered again to ensure the quality of the coating film.

[0050] The method for manufacturing a piezoelectric film-coated laminated substrate according to the present invention is a method that can efficiently form a piezoelectric film on a target substrate while ensuring quality such as piezoelectric performance.

[0051] This is a schematic plan view showing the general mechanism of a film substrate manufacturing method, which is an example of a method for manufacturing a piezoelectric film-attached laminated substrate according to the present invention. This is a photograph of the film substrate after the 15th firing in Example 1. This is an image showing the results of operational verification of an ultrasonic array sensor manufactured using the film substrate of Example 1. This is a photograph of the film substrate after the 15th firing in Comparative Example 1. This is a photograph of the film substrate after the 11th firing in Comparative Example 2. This is a photograph of the film substrate after the 1st firing in Comparative Example 3. This is a schematic diagram of the structure of a film substrate on which a piezoelectric film is fixed using a polymer adhesive. (a) is a schematic diagram showing an example of a path when moving the substrate with respect to the tip of a fixed coating spray gun, and (b) is a graph showing the relationship between the film thickness of the coating film formed on the substrate and the distance traveled in the direction of travel when the substrate is moved along the path shown in Figure 8(a).

[0052] The following describes embodiments of the present invention to facilitate understanding of the present invention.

[0053] This section describes a method for manufacturing a film substrate, which is an example of a method for manufacturing a piezoelectric film-coated substrate according to the present invention. In the following, the piezoelectric film-coated laminate substrate to be manufactured will be referred to as the "film substrate."

[0054] Here, manufacturing mechanism A used in the method for manufacturing a film substrate has various devices related to the manufacturing of the film substrate arranged inside, and is a mechanism for manufacturing a film substrate by laminating a piezoelectric film onto a target substrate.

[0055] As shown in Figure 1, the manufacturing mechanism A has a box-shaped acrylic box 1. The acrylic box 1 is installed in a predetermined indoor space or the like and is a component that constitutes the outer shape of the manufacturing mechanism A. The acrylic box 1 has four sides and one top surface and is a partition member that separates the indoor space from the inside of the manufacturing mechanism A.

[0056] Furthermore, manufacturing mechanism A has a low-humidity gas supply unit (not shown), which supplies dry air into the acrylic box 1, thereby enabling control of the humidity of the internal environment of the acrylic box 1.

[0057] Furthermore, manufacturing mechanism A has a temperature control mechanism (not shown) that allows for control of the internal temperature of the acrylic box 1.

[0058] Furthermore, as shown in Figure 1, the acrylic box 1 is equipped with a transport section 2, a spray coating section 3, a drying and cooling section 4, and a firing section 5.

[0059] Here, the transport unit 2 is the part that transports the substrate inside the acrylic box 1. The spray coating unit 3 is the part that applies a coating that will become a piezoelectric film onto the substrate.

[0060] Furthermore, the drying and cooling section 4 is the part on which the substrate is placed in order to dry the piezoelectric material solution sprayed onto the substrate before firing. The drying and cooling section 4 is also the part on which the fired substrate is placed in order to cool it before spray coating again.

[0061] Furthermore, the firing section 5 is the part that fires the piezoelectric material solution sprayed onto the substrate to form a coating film.

[0062] Furthermore, the transport unit 2 has a robotic arm 20 capable of gripping and transporting substrates. The robotic arm 20 can transport the substrates within the acrylic box 1 toward the spray coating unit 3, the drying and cooling unit 4, and the firing unit 5, and is responsible for moving the substrates between various processing steps.

[0063] Furthermore, a substrate placement section (not shown) is provided near the robot arm 20, where substrates before processing for manufacturing film substrates and film substrates after manufacturing are placed. The robot arm 20 is configured to transport the unprocessed substrates supplied to the substrate placement section and provide them for various processing steps.

[0064] Furthermore, the robot arm 20 is driven via a control unit (not shown), and the transport of the substrate is configured to grasp and transport the substrate according to a preset processing procedure.

[0065] Here, the transport unit 2 does not necessarily need to have a robot arm 20, and other transport mechanisms can be used. For example, a belt conveyor, AGV (Auto Guided Vehicle), AMR (Autonomous Mobile Robot), or other known transport means used in factories can be used as the transport mechanism.

[0066] Furthermore, specific examples of known transport methods are as follows: AGV (Automated Guided Vehicle): An autonomous vehicle that transports parts along a designated route. AMR (Autonomous Mobile Robot): Unlike AGVs, it can calculate its route in real time and move, offering high flexibility. Linear motor conveyor: Uses magnetism to transport parts quickly and accurately. Lift-type transport device: Capable of transporting parts horizontally and vertically. Screw conveyor: Transports powders and granular parts by rotating a screw. Bucket elevator: A continuous transport machine for transporting parts vertically. (Hybrid and special transport methods) Forklift: Capable of transporting parts along with their pallets. Drone transport: Moves lightweight parts through the air (suitable for special environments and wide areas). (Transport methods that assist human power) Cart with casters: A simple manual transport method. Slider platform: Transports parts by sliding them. Roller conveyor: Moves light parts manually or by gravity. (Others) Vacuum suction transport device: Uses vacuum to suction and transport parts. Magnetic lifter: Moves by attracting magnetic materials. Crane system: Transports heavy objects and large parts.

[0067] Furthermore, the spray coating unit 3 has a box-shaped acrylic coating box 30. The acrylic coating box 30 is a smaller box shape than the acrylic box 1 described above, and is a component that further partitions the space inside the acrylic box 1 for spray coating onto the substrate.

[0068] Furthermore, the coating acrylic box 30 can be supplied with dry air from the low-humidity gas supply unit mentioned above, allowing for control of the humidity of the internal environment of the coating acrylic box 30.

[0069] Furthermore, the internal environment of the acrylic box 1 and the internal environment of the coating acrylic box 30 are configured to allow for individual humidity control via a low-humidity gas supply unit.

[0070] Furthermore, the spray coating unit 3 has a temperature control mechanism (not shown) that allows for control of the internal temperature of the coating acrylic box 30.

[0071] Furthermore, the spray application unit 3 includes a holding jig (not shown) and a spray gun for application. The holding jig and the spray gun are located inside the acrylic box 30 for application, with the spray gun attached to the holding jig.

[0072] Furthermore, a slit is formed in a part of the side of the acrylic coating box 30, through which the tip of the robot arm 20 holding the substrate can pass. This allows the tip of the robot arm 20 holding the substrate to move the substrate even inside the acrylic coating box 30.

[0073] In this spray coating section 3, the tip of the robot arm 20, which is gripping the substrate, enters the inside of the coating acrylic box 30, and the coating spray gun applies the piezoelectric material solution to the held substrate.

[0074] Furthermore, the spray gun for coating is controlled via a control unit (not shown) and is configured to spray coating onto the substrate according to a preset processing procedure.

[0075] Furthermore, when applying the piezoelectric material solution to the substrate, a mask member with multiple slits is placed on top of the substrate, and a spray gun for application is configured to apply a fixed amount of solution from above the mask member. The robot arm 20 also holds the mask member together with the substrate.

[0076] In other words, the piezoelectric material solution that has passed through the regions of multiple slits in the mask member is applied to the substrate, or onto a coating film formed on the substrate.

[0077] Furthermore, the spray coating section 3 is equipped with a vibrator to apply vibration to the substrate held by the robot arm 20. By applying vibration to the substrate coated with the piezoelectric material solution, the piezoelectric material solution can be more easily filled into the recesses on the surface of the substrate.

[0078] Furthermore, when a coating film is formed after the substrate has been fired, and a piezoelectric material solution is spray-applied onto the coating film using a spray gun, similarly, vibration can be applied with a vibrator to facilitate the filling of depressions, gaps, and pores on the surface of the coating film with the piezoelectric material solution.

[0079] Furthermore, the spray coating unit 3 is provided with an imaging unit (not shown). This imaging unit acquires an image of the substrate surface or the coating surface before or after spray coating the piezoelectric material solution.

[0080] This imaging unit can acquire images of the substrate surface or coating surface, and the surface shape can be inspected based on the acquired images.

[0081] For example, after spray-coating a piezoelectric material solution, the degree to which the piezoelectric material solution fills depressions and gaps on the surface of a substrate (such as the extent of unfilled depressions) can be observed, and if certain standards are not met, measures such as re-coating the solution can be taken. Furthermore, a CCD camera or similar imaging device can be used to inspect for foreign matter on the surface.

[0082] Furthermore, as shown in Figure 1, the drying and cooling section 4 has a heat-resistant metal base 40. The heat-resistant base 40 is a platform-shaped member larger than the substrate, and is the part on which the substrate after spray coating or the substrate after firing, which has become hot, is placed.

[0083] Furthermore, as shown in Figure 1, the firing section 5 has a firing furnace 50. The firing furnace 50 also has a temperature and humidity control device, which is configured to control the temperature and humidity inside the furnace to constant values ​​when firing substrates inside the furnace 50.

[0084] Next, we will explain the process for manufacturing a film substrate using manufacturing mechanism A. The following description is an example of a method for manufacturing a piezoelectric laminate substrate to which the present invention is applied.

[0085] First, as a piezoelectric material solution to be applied to the substrate, lead zirconate titanate (PZT) sol gel solution and PZT powder were mixed in a certain ratio and stirred in a ball mill for more than 24 hours to obtain the piezoelectric material solution.

[0086] Furthermore, a stainless steel (SUS304) substrate was used as the base substrate for manufacturing the film substrate.

[0087] Here, the piezoelectric material solution does not necessarily have to consist of a lead zirconate titanate (PZT) sol-gel solution and PZT powder; other sol-gel solutions and powdered raw materials can be used.

[0088] For example, as a sol-gel solution, a piezoelectric material having piezoelectric properties due to the anisotropy of its crystals can be used in a state between sol and gel, known as a sol-gel. As the piezoelectric material, for example, lead zirconate titanate (PZT) as described above can be used. Furthermore, lithium niobate and other piezoelectric materials with known piezoelectric properties can be used as raw materials in a sol-gel form.

[0089] Furthermore, as the powder, a piezoelectric material having piezoelectric properties due to the anisotropy of its crystals can be used in powder form. For example, lead zirconate titanate (PZT) as described above can be used. In addition, lithium niobate and other piezoelectric materials with known piezoelectric properties can be used as raw materials in powder form.

[0090] Furthermore, the sol-gel solution and powder that constitute the piezoelectric material solution do not necessarily need to possess piezoelectric properties themselves; it is sufficient if the combined sol-gel solution and powder possess piezoelectric properties.

[0091] Furthermore, it is not necessarily required that a SUS304 substrate be used as the base substrate for manufacturing the film substrate; substrates used in known film substrates can be used. For example, substrates such as SUS304, SUS430, titanium, copper, and aluminum can be used.

[0092] Furthermore, the internal environment of the acrylic box 1 is controlled via a low-humidity gas supply unit to maintain a relative humidity of 40% or less, in order to substantially fill the minute surface recesses on the substrate with a piezoelectric material solution. The internal environment of the acrylic box 1 is also controlled to a temperature of 25°C via a temperature control mechanism.

[0093] Here, the internal environment of the acrylic box 1 can be set to, for example, a relative humidity of 40% or less, or a relative humidity of 20% or less, in order to substantially fill the minute surface recesses on the substrate with the piezoelectric material solution.

[0094] Furthermore, in the transport unit 2, the robot arm 20 grasps the substrate placed in the substrate mounting unit and transports the substrate to the spray coating unit 3.

[0095] Furthermore, the tip of the robot arm 20, which has passed through the slit in the coating acrylic box 30, holds the mask member on top of the substrate, and the robot arm 20 faces the coating spray gun, which is fixed by a holding jig.

[0096] In this process, the internal environment of the coating acrylic box 30 is controlled via a low-humidity gas supply unit to maintain a relative humidity of 40% or less, in order to substantially fill the minute surface recesses on the substrate with the piezoelectric material solution. Furthermore, the internal environment of the coating acrylic box 30 is controlled to a temperature of 25°C via a temperature control mechanism.

[0097] Here, the internal environment of the coating acrylic box 30 can be set to, for example, a relative humidity of 40% or less, or a relative humidity of 20% or less, in order to substantially fill the minute surface recesses on the substrate with the piezoelectric material solution.

[0098] Then, based on a pre-set program control, the power to the coating spray gun is turned ON, and the piezoelectric material solution is sprayed from the coating spray gun. The tip of the robot arm 20 moves the substrate in response to this, so that the solution is uniformly applied to the substrate, adding slits to the mask member.

[0099] Furthermore, once a certain amount of piezoelectric material solution has been sprayed, the power to the coating spray gun is turned OFF, the robot arm 20 removes the mask member, and moves the substrate outside the coating acrylic box 30.

[0100] The robot arm 20 then transports the substrate from the spray coating unit 3 onto the heat-resistant base 40 of the drying and cooling unit 4, and dries the applied piezoelectric material solution on the substrate on the heat-resistant base 40 for about 5 to 10 minutes.

[0101] Furthermore, after drying the substrate in the drying and cooling section 4, the robot arm 20 transports the substrate into the firing furnace 50 of the firing section 5. Inside the firing furnace 50, the substrate is separated from the tip of the robot arm 20 at the position where firing takes place, and the substrate is set in a predetermined position.

[0102] Furthermore, in the firing furnace 50, the substrate is fired at a temperature of 400°C to 650°C for about 3 to 5 minutes. This firing causes the piezoelectric material solution applied by the spray coating section 3 to solidify, forming a coating film on the substrate.

[0103] In this process, in order to substantially fill the minute surface depressions on the substrate with the piezoelectric material solution, the internal environment of the firing furnace 50 is controlled via a temperature and humidity control device so that the relative humidity is 40% or less.

[0104] Here, the internal environment of the firing furnace 50 can be set to, for example, a relative humidity of 40% or less, or a relative humidity of 20% or less, in order to reduce moisture that would prevent the piezoelectric material solution from filling minute surface depressions on the substrate.

[0105] After the firing process in the firing furnace 50, the robot arm 20 grasps the substrate, and the substrate is transported onto the heat-resistant base 40 of the drying and cooling section 4. The substrate, which has become hot due to firing, is placed on the heat-resistant base 40 for about 10 minutes to cool down.

[0106] After the substrate is cooled in the drying and cooling section 4, the robot arm 20 transports the substrate to the spray coating section 3.

[0107] Following this, the piezoelectric material solution is spray-coated onto the coating formed on the substrate, in the same manner as described above. Similarly, the substrate is then dried, fired, and cooled.

[0108] Thus, when spray-coating a piezoelectric material solution onto a coating film (first coating layer) formed on a substrate to form another coating film (second coating layer), the same process described above is followed to substantially fill minute depressions, gaps, or pores on the surface of the first coating layer with the piezoelectric material solution that will become the second coating layer. Furthermore, "substantially filling" here also includes filling depressions, gaps, or pores on the surface of the coating film (e.g., the first coating layer) that were formed earlier, during the second and subsequent spray-coating processes.

[0109] Furthermore, when spray-coating a piezoelectric material solution onto a coating film (first coating layer) formed on a substrate to form another coating film (second coating layer), cooling the substrate before the spray coating process can remove the heat generated during the firing of the first coating layer.

[0110] According to this method, when a piezoelectric material solution is spray-applied onto the first coating layer, the piezoelectric material solution evaporates due to heat, preventing the formation of minute depressions, gaps, pores, etc., on the surface of the resulting coating (second coating layer). As a result, the peeling of the coating layered on the substrate can be prevented.

[0111] In this process, from spray coating to substrate cooling, a coating film approximately 10 μm thick can be formed. Therefore, by performing the spray coating and substrate firing processes multiple times, multiple coating films can be layered on the substrate, and the desired thickness can be achieved for the entire layered coating film.

[0112] Furthermore, after performing spray coating and substrate firing processes multiple times to form a coating of the desired thickness, a corona discharge polarization device is used to apply a voltage (for example, 30 kV per 100 μm) to the coating to perform polarization treatment. This polarization treatment imparts piezoelectricity to the coating.

[0113] By adding electrodes and wiring to a substrate that has undergone this polarization treatment, sensors such as ultrasonic array sensors can be constructed.

[0114] Furthermore, regarding the film substrate manufactured here, the piezoelectric constant (d3) that indicates the piezoelectric performance of the piezoelectric film is used. ３３When measured, the result is 50 pC / N or higher, indicating that a piezoelectric film with good piezoelectric performance can be formed.

[0115] Furthermore, regarding the film substrate described above, in order to prevent the piezoelectric film from peeling off, it is conceivable that the piezoelectric film may be fixed to the substrate using a polymer adhesive.

[0116] In the structure shown in Figure 7, a piezoelectric film (PZT layer) 101 is laminated onto a SUS plate 100 using the method described above, and an upper electrode 102 is provided on top of it. A polymer adhesive 103 is then applied to the piezoelectric film 101 to fix it to the SUS plate 100.

[0117] This polymer adhesive 103 is applied to the area of ​​the piezoelectric film 101 where the upper electrode 102 is not attached, and to the SUS plate 100. This polymer adhesive 103 is composed of an insulating epoxy adhesive.

[0118] In the structure shown in Figure 7, the piezoelectric film 101 is fixed to the SUS plate 100 by the polymer adhesive 103, thereby preventing the piezoelectric film 101 from peeling off from the SUS plate 100.

[0119] Furthermore, the electrode 105 of the FPC 104 is fixed to the upper electrode 102 via an anisotropic conductive adhesive 106.

[0120] Here, by fixing the piezoelectric film 101 with polymer adhesive 103, when an external force is generated that would cause the piezoelectric film 101 to peel off due to the elasticity of the FPC 104, it is possible to prevent the piezoelectric film 101 from peeling off from the SUS plate 100.

[0121] Furthermore, since the polymer adhesive 103 is insulating, it is possible to prevent the electrodes 105 of the FPC 104 from making unintended electrical contact with the piezoelectric film 101 or the SUS plate 100 (lower electrode).

[0122] Here, the polymer adhesive 103 can be appropriately selected as long as it is a component that can be cured to fix the piezoelectric film 101 and has insulating properties.

[0123] Furthermore, the polymer adhesive 103 can be attached not only by application, but also by immersing the SUS plate 100 and the piezoelectric film 101 in the liquid polymer adhesive before it hardens, thereby adhering them to desired locations on the SUS plate 100, etc.

[0124] Furthermore, the polymer adhesive 103 can be attached to the piezoelectric film 101 either after or before the upper electrode 102 is installed.

[0125] Thus, in the method for manufacturing a film substrate to which the present invention is applied, peeling of the piezoelectric film from the substrate can be prevented by using a polymer adhesive.

[0126] In the manufacturing method of a film substrate using the manufacturing mechanism A described above, the humidity is controlled to be low so that the relative humidity is 40% or less in the internal environment of each of the various processes performed in the spray coating section 3, the drying and cooling section 4, and the firing section 5. This makes it possible to substantially fill minute surface recesses on the substrate, as well as minute surface recesses, gaps, or pores in the coating film laminated on the substrate, with the piezoelectric material solution.

[0127] First, by controlling the relative humidity of the internal environment in the spray coating section 3 to 40% or less, the adverse effects of ambient humidity on the paint on the substrate after spray coating and before it hardens through firing can be reduced, thereby preventing unevenness and cracking in the coating film after firing. In addition, it is possible to prevent a decrease in the piezoelectric performance of the piezoelectric film due to the effects of humidity.

[0128] Furthermore, by controlling the relative humidity in the internal environment where the drying and cooling unit 4 is provided, i.e., the internal environment of the acrylic box 1, to 40% or less, the adverse effects of humidity in the environment during the drying of the piezoelectric material solution coating applied to the substrate can be reduced, thereby preventing unevenness and cracking in the coating film after firing. In addition, it is possible to prevent a decrease in the piezoelectric performance of the piezoelectric material film due to the effects of humidity.

[0129] In particular, when drying the substrate in the drying and cooling section 4, when spray-applying paint on top of the coating already formed on the substrate to create a layer of coatings, the paint applied from above adheres more easily to the surface of the lower coating, making it easier to form a strong coating that is less prone to peeling overall.

[0130] Furthermore, by controlling the relative humidity inside the acrylic box 1 to 40% or less, it becomes possible to reduce the adverse effects of ambient humidity on the coating film when the robot arm 20 transports the substrate.

[0131] Furthermore, by controlling the relative humidity of the internal environment in the firing furnace 50 of the firing section 5 to 40% or less, the adverse effects of ambient humidity on the paint on the substrate before firing and on the coating film shortly after firing can be reduced, thereby preventing unevenness and cracking in the coating film after firing. In addition, it is possible to prevent a decrease in the piezoelectric performance of the piezoelectric material film due to the effects of humidity.

[0132] Next, we will explain a modified version of manufacturing mechanism A.

[0133] In the manufacturing mechanism A described above, the firing section 5 had a firing furnace 50, but a hot plate can be used instead of the firing furnace 50.

[0134] In this case, the substrate dried in the cooling and drying section 4 is transported to the hot plate via the robot arm 20, where it is heated and fired. Furthermore, in this modified example, the humidity inside the acrylic box 1 is controlled, allowing for the formation of a good coating film.

[0135] Next, we will describe other embodiments of the manufacturing process for film substrates using the manufacturing mechanism A described above. Note that the following description will only cover the changes in the other embodiments, and will omit explanations of aspects common to the manufacturing process for film substrates using the manufacturing mechanism A described above.

[0136] In another embodiment of the present invention, a coating manufacturing section is provided inside the acrylic box 1 in the manufacturing mechanism A. This coating manufacturing section is a part that forms a coating film on a substrate or on a coating film formed on a substrate using a piezoelectric material solution by a spin coating method.

[0137] In other words, in addition to the formation of a coating film by the spray application unit 3, it is also possible to form a coating film with a piezoelectric material solution by the coating film manufacturing unit.

[0138] Furthermore, in the coating manufacturing section, a spin coater that applies piezoelectric material solution onto substrates or coating films is located inside a box-shaped acrylic box. Dry air is supplied to the inside of this acrylic box from a low-humidity gas supply unit, allowing for control of the humidity of the internal environment.

[0139] Here, the acrylic box for the coating production section is provided separately from the acrylic box 30 for application in the spray application section 3. Furthermore, the humidity inside the acrylic box for the coating production section is adjusted to be the same as that of the acrylic box 30 for application.

[0140] Furthermore, the transport unit 2 is capable of transporting substrates within the acrylic box 1 via the robot arm 20 towards the coating manufacturing unit, the spray coating unit 3, the drying and cooling unit 4, and the firing unit 5.

[0141] Furthermore, the drying and cooling section 4 is capable of drying the piezoelectric material solution applied in the coating manufacturing section before firing. In addition, the firing section 5 is capable of firing the piezoelectric material solution applied in the coating manufacturing section to form a coating film.

[0142] Thus, in another embodiment of the present invention, when forming a piezoelectric film on a substrate by laminating it, the piezoelectric film can be formed by including both the layer applied in the coating manufacturing section and the layer applied in the spray coating section 3.

[0143] Here, it is not necessarily required that the coating manufacturing department use a spin coater to apply the piezoelectric material solution. For example, an approach can be adopted in which a roll coater is used instead of a spin coater to apply the piezoelectric material solution by a roll coating method.

[0144] Furthermore, the coating manufacturing unit may also adopt a method of forming thin films by sputtering instead of spin coating.

[0145] Furthermore, in other embodiments of the present invention, it is not necessarily required that the relative humidity of the environment in which each of the coating production section, spray application section 3, drying and cooling section 4, and baking section 5 is performed be controlled to be below a predetermined value.

[0146] Furthermore, in another embodiment of the present invention, in the coating films to be laminated on a substrate, the viscosity of each coating film can be made different between the nth layer and the (n+1)th layer.

[0147] For example, when the (n+1)th layer is the topmost layer of a piezoelectric film-coated laminated substrate, by adjusting the viscosity of the (n+1)th layer's coating film to be lower than that of the (n)th layer's coating film, the (n+1)th layer's coating film can be covered with the lower viscosity coating film, thereby improving the adhesion between the two layers.

[0148] Furthermore, the viscosity between the nth and (n+1)th coating layers can be adjusted, for example, by adjusting the proportions of the sol-gel solution and powder that constitute the piezoelectric material solution, or by adding a viscosity modifier or adhesive to the piezoelectric material solution, thereby making the viscosity of each coating layer different.

[0149] Furthermore, in other embodiments of the present invention, it is not necessarily required that the viscosity of the coating film differs only between the nth layer and the (n+1)th layer of coating film laminated on the substrate. For example, it is possible to form the coating film with different viscosities in combinations between the (n-1)th layer and the nth layer, or in combinations of upper and lower layers of coating film located away from the nth layer. Moreover, the viscosity of the coating film can be varied not only between two layers, but also across three or more layers. These embodiments are also applicable to structures described below, such as structures in which the mixing ratio of sol-gel solution and powder in the piezoelectric material solution is varied for each coating film, or structures in which the particle size of the powder in the piezoelectric material solution is varied.

[0150] Furthermore, in another embodiment of the present invention, the viscosity of the first coating layer (first coating layer) formed on the substrate can be adjusted to form a coating film between the substrate and the substrate. By adjusting the viscosity, the adhesion of the first coating layer to the surface of the substrate can be improved, making it less likely for the first coating layer to peel off from the surface of the substrate.

[0151] Furthermore, in another embodiment of the present invention, in the coating films laminated on a substrate, the mixing ratio of the sol-gel solution and powder in the piezoelectric material solution constituting each coating film can be made different between the nth layer and the (n+1)th layer.

[0152] In this way, by varying the mixing ratio of the sol-gel solution and powder in the piezoelectric material solution between the nth layer and the (n+1)th layer of coating, the density and water activity of each coating become different. As a result, the properties of the nth layer and the (n+1)th layer of coating change as if they were formed from different materials, and the adhesion between the two layers can be improved.

[0153] Furthermore, the content of differentiating the mixing ratio of the sol-gel solution and powder in the piezoelectric material solution between the nth layer coating and the (n+1)th layer coating may include cases where one of the nth layer coating or the (n+1)th layer coating contains the sol-gel solution and powder, and the other has a mixing ratio of "sol-gel solution:powder = 0:100".

[0154] Furthermore, in another embodiment of the present invention, the mixing ratio of the sol-gel solution and powder in the piezoelectric material solution of the first coating layer between the substrate and the coating film (first coating layer) formed on the substrate is adjusted to change the density and water activity of the coating film, thereby improving the adhesion of the first coating layer to the surface of the substrate and making it less likely for the first coating layer to peel off from the surface of the substrate.

[0155] Furthermore, in another embodiment of the present invention, in the coating films laminated on a substrate, the particle size of the powder before mixing with the sol-gel solution in the piezoelectric material solution constituting each coating film can be made different between the nth layer and the (n+1)th layer.

[0156] In this context, "powder particle size" refers to the average diameter of the powder before it is mixed with the sol-gel solution.

[0157] In this way, by making the particle size of the powder before mixing with the sol-gel solution in the piezoelectric material solution different between the nth layer and the (n+1)th layer of coating, the density and porosity of each coating become different. As a result, the properties of the nth layer and the (n+1)th layer of coating change as if they were formed from different materials, and the adhesion between the two layers can be improved.

[0158] Furthermore, in another embodiment of the present invention, the particle size of the powder before mixing with the sol-gel solution in the piezoelectric material solution of the first coating layer between the substrate and the coating film (first coating layer) formed on the substrate is adjusted to change the density and porosity of the coating film, thereby improving the adhesion of the first coating layer to the surface of the substrate and making it less likely for the first coating layer to peel off from the surface of the substrate.

[0159] Furthermore, in another embodiment of the present invention, in the coating film to be laminated on a substrate, the thickness of each coating film can be made different between the nth layer and the (n+1)th layer.

[0160] For example, when forming multiple layers up to the nth layer by spray coating, and then further forming a coating by spray coating the (n+1)th layer to a thickness greater than the (n)th layer, the amount of particles in the (n+1)th layer of coating that are absorbed by the coatings below the nth layer increases, thereby improving the adhesion between the two layers.

[0161] Furthermore, the film thickness between the nth and (n+1)th coating layers can be adjusted by, for example, the following methods: (1) In the case of spray coating, adjusting the distance between the tip of the fixed spray gun from which the piezoelectric material solution is sprayed and the object to be coated (substrate or coating on the substrate). (2) In the case of spray coating, adjusting the relative movement speed between the spray gun and the object to be coated (substrate or coating on the substrate). This relative movement speed is, for example, the movement speed when the substrate 100 held by a robot hand (not shown) is moved along the path indicated by the symbol L in the figure relative to the tip 300 of the fixed spray gun. The symbol T in the figure indicates the range on the substrate 100 where the piezoelectric material solution is sprayed (more piezoelectric material solution is sprayed towards the center of range T than towards the outside). (3) In the example of Figure 8(a) described above, adjusting the movement interval I in the direction of travel along the path indicated by the symbol L in the figure. In this method, increasing the distance I traveled in the direction of travel reduces the peak portion of the graph shown in Figure 8(b) (thinning the film thickness), and decreasing the distance I traveled in the direction of travel increases the peak portion of the graph shown in Figure 8(b) (thickening the film thickness). In Figure 8(b), the vertical axis represents film thickness (μm), and the horizontal axis represents the distance traveled in the direction of travel (nm). (4) A method for adjusting the opening degree of the nozzle at the tip of the spray gun for spray coating. (5) A method for adjusting the spray pressure of the spray gun for spray coating (air pressure from the compressor that serves as the driving source).

[0162] Furthermore, in another embodiment of the present invention, the coating film can be formed by adjusting the thickness of the first coating film (first coating film layer) between the substrate and the coating film formed on the substrate. By adjusting the thickness, the adhesion of the first coating film layer to the surface of the substrate can be improved, making it more difficult for the first coating film layer to peel off from the surface of the substrate.

[0163] Furthermore, in other embodiments of the present invention, it is possible to make the nth layer of the coating film and the (n+1)th layer of the coating film laminated on the substrate differ in combination. For example, the viscosity of the coating film, the mixing ratio of the sol-gel solution and powder in the piezoelectric material solution, the particle size of the powder before mixing with the sol-gel solution, and the thickness of the coating film may be made different, or some of these properties may be made different.

[0164] Furthermore, in other embodiments of the present invention, the viscosity of each coating film may be made different between two vertically connected layers in the coating film laminated on the substrate, and the mixing ratio of the sol-gel solution and powder (or the particle size of the powder) in the piezoelectric material solution of each coating film may be made different between two other vertically connected layers.

[0165] As described above, the method for manufacturing a piezoelectric film-coated laminated substrate to which the present invention is applied is a method that can efficiently form a piezoelectric film on the target substrate while ensuring quality such as piezoelectric performance.

[0166] [Examples] Examples and comparative examples of the present invention will be described below.

[0167] (Example 1) A modified version of the manufacturing mechanism A described above (using a hot plate in the firing section 5) was used to manufacture a film substrate according to the following procedure. A SUS304 substrate measuring 120 mm × 120 mm × 0.05 mm was used. The day before the test, a lead zirconate titanate (PZT) sol gel solution and PZT powder were mixed and stirred in a ball mill machine. The untreated substrate was transported by a robot arm 20, and the piezoelectric material solution was spray-coated onto the substrate in the spray coating section 3. The coated substrate was then dried for 5 to 8 minutes in the cooling and drying section 4. After that, the substrate was transported to a hot plate and fired at 450°C for 3 minutes. After firing, the substrate was cooled in the cooling and drying section 4 for 8 minutes. Thereafter, spray coating, drying, firing, and cooling were repeated, and a total of 15 spray coatings were performed. Furthermore, the relative humidity in the spray coating section 3 (inside the coating acrylic box 30), the drying and cooling section 4, and the firing section 5 (inside the acrylic box 1) was set to 16%. The 15th firing was performed at a temperature of 650°C for 3 minutes. After cooling, the substrate was subjected to polarization treatment using a corona discharge polarization device, and this was designated as Example 1.

[0168] For the film substrate of Example 1, d ３３ Using a meter (model ZJ-3B, manufactured by the Institute of Acoustics, Chinese Academy of Sciences), the piezoelectric constant (d) of the piezoelectric film was determined. ３３ The following parameters were measured. In addition, electrodes and wiring were provided on the film substrate of Example 1 to construct an ultrasonic array sensor, and its operation was verified.

[0169] Figure 2 is a photograph of the film substrate after the fifth firing in Example 1. As shown in Figure 2, the film substrate S1 of Example 1 has a neatly laminated piezoelectric film and a coating with a good appearance.

[0170] Piezoelectric constant (d) of Example 1 ３３ The ratio was 70 pC / N. Furthermore, the film thickness of the PZT film deposited in Example 1 was 147 μm.

[0171] Figure 3 shows the results of the operational verification of the ultrasonic array sensor manufactured using the membrane substrate of Example 1. Figure 3 is a B-mode image of the string target. In this image, the upper part of the figure is near the body surface, and the lower part is deep inside the body. The further down (deeper) the white dots are visible in the figure, the better the sensor is, and the smaller each white dot appears, the better the sensor is. As shown in Figure 3, small white dots were observed in the lower part of the figure.

[0172] (Example 2) A film substrate was prepared using the same method as in Example 1, except for the conditions described below, and this was designated as Example 2. Spray coating, drying, firing, and cooling were repeated, resulting in a total of 13 spray coatings. In addition, the relative humidity in each space of the spray coating section 3 (inside the coating acrylic box 30), the drying and cooling section 4, and the firing section 5 (inside the acrylic box 1) was kept within the range of 22-35%.

[0173] Piezoelectric constant (d) of Example 2 ３３ The ratio was 59 pC / N. In addition, the film thickness of the PZT film deposited in Example 2 was 97 μm.

[0174] (Example 3) A film substrate was prepared using the same method as in Example 1, except for the conditions described below, and this was designated as Example 3. The relative humidity in the spray coating section 3 (inside the coating acrylic box 30), the drying and cooling section 4, and the firing section 5 (inside the acrylic box 1) was kept within the range of 24-29%.

[0175] Piezoelectric constant (d) of Example 3 ３３ The ratio was 60 pC / N. In addition, the film thickness of the PZT film deposited in Example 3 was 120 μm.

[0176] Next, following the same procedure as in Example 1 above, film substrates were manufactured in the spray coating section 3 (inside the coating acrylic box 30), the drying and cooling section 4, and the firing section 5 (inside the acrylic box 1) without humidity control, using the laboratory environment, and these were used as various comparative examples.

[0177] (Comparative Example 1) In Comparative Example 1, the relative humidity in the laboratory was 58%. In Comparative Example 1, unevenness was observed in the coating film on the substrate after the first spray coating and firing. Furthermore, after the 15th spray coating and firing, cracks occurred in the coating film on substrate S2, as shown in Figure 4.

[0178] (Comparative Example 2) Comparative Example 2 was tested on a different day than Comparative Example 1, and the relative humidity in the laboratory was 66%. In Comparative Example 2, after the first spray coating and firing, rosettes (crystal-like lumps) were observed in the coating film on the substrate. Furthermore, after the eleventh spray coating and firing, cracks occurred in the coating film on substrate S3, as shown in Figure 5. In addition, the piezoelectric constant (d) of the piezoelectric film was measured in areas without cracks. ３３ The measurement of ) was found to be 30 pC / N.

[0179] (Comparative Example 3) Comparative Example 3 was tested on a different day than Comparative Examples 1 and 2, and the relative humidity in the laboratory was 70%. In Comparative Example 3, as shown in Figure 6, rosettes (crystal-like clumps) were observed in the coating film on the substrate S4 after the first spray coating and firing. Furthermore, large cracks appeared in the coating film after the third spray coating and firing.

[0180] (Comparative Example 4) Comparative Example 4 was tested on a different day than Comparative Examples 1-3, and the relative humidity in the laboratory was within the range of 42-57%. In Comparative Example 4, after the 10th spray application, unevenness in the coating film was observed, visible to the naked eye and through image analysis.

[0181] A. Manufacturing mechanism 1. Acrylic box 2. Conveying unit 20. Robot arm 3. Spray coating unit 30. Acrylic box for coating 4. Drying and cooling unit 40. Heat-resistant base 5. Firing unit 50. Firing furnace

Claims

1. A method for manufacturing a laminated substrate with a piezoelectric film, comprising: a base step of applying or adhering the piezoelectric material solution to the substrate in order to substantially fill at least one of the following with the piezoelectric material solution: recesses on the surface of the substrate, recesses on the surface of the coating film which will become the piezoelectric film laminated on the substrate, gaps in the coating film, or pores in the coating film; a heat treatment step of heat treating the substrate after the base step; and a transport step of transporting the substrate between the base step and the heat treatment step via a transport unit for transporting the substrate; wherein the base step and the heat treatment step are performed multiple times to laminate the coating film on the substrate, and the properties of predetermined properties differ between the substrate and the first layer of coating film on the substrate, and / or between at least one pair of n-th layer and n+1-th layer of coating films among the laminated coating films. A method for manufacturing a laminated substrate with a piezoelectric film, wherein at least one of the laminated coating films is applied to the substrate by spray coating in the basic step, using the piezoelectric material solution.

2. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1, wherein the predetermined property is the film thickness.

3. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1 or claim 2, wherein the predetermined property is the particle size of the powder before it is mixed with the sol-gel solution to form the composite.

4. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1 or claim 2, wherein the predetermined property is the mixing ratio of the sol-gel solution and the powder in the composite.

5. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1 or claim 2, wherein the predetermined property is viscosity.

6. A method for manufacturing a laminated substrate with a piezoelectric film according to claim 1 or 2, further comprising a vibration step of vibrating the substrate after applying or adhering the piezoelectric material solution to the substrate in the basic step.

7. A method for manufacturing a laminated substrate with a piezoelectric film according to claim 1 or 2, wherein the basic process is carried out in a first atmosphere, the heat treatment process is carried out in a second atmosphere, the transport process transports the substrate in the first atmosphere and the second atmosphere, and the first atmosphere and the second atmosphere are controlled so that the relative humidity is below a predetermined value.

8. The method for manufacturing a piezoelectric film-equipped laminated substrate according to claim 7, wherein the first atmosphere and the second atmosphere are controlled to have a relative humidity of 40% or less.

9. A method for manufacturing a laminated substrate with a piezoelectric film, comprising forming a piezoelectric film on a substrate using a piezoelectric material solution containing a composite of a sol-gel solution and a powder, the method comprising: a coating step of spray-applying the piezoelectric material solution to the substrate under a first atmosphere in order to substantially fill at least one of the recesses on the substrate surface, recesses on the surface of a coating film that will become the piezoelectric film laminated on the substrate, gaps in the coating film, or pores in the coating film with the piezoelectric material solution; a heat treatment step of heat-treating the spray-coated substrate under a second atmosphere; and a transport step of transporting the substrate between the coating step and the heat treatment step via a transport unit that transports the substrate under the first atmosphere and the second atmosphere, wherein the relative humidity of the first atmosphere and the second atmosphere is controlled to be below a predetermined value, and the coating step and the heat treatment step are performed multiple times to laminate the coating film onto the substrate.

10. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1 or claim 9, wherein the heat treatment step includes at least one of the following steps: a firing step for firing the substrate, a drying step for drying the substrate, or a cooling step for cooling the fired substrate.

11. A method for manufacturing a laminated substrate with a piezoelectric film according to claim 1 or 9, comprising a coating film fixing step of fixing a plurality of coating films laminated on the substrate to the substrate using an insulating polymer adhesive.

12. The method for manufacturing a laminated substrate with a piezoelectric film according to claim 9, further comprising a vibration step of vibrating the substrate after spray coating the piezoelectric material solution in the coating step.

13. A method for manufacturing a laminated substrate with a piezoelectric film according to claim 1 or claim 9, comprising an inspection step for inspecting the substrate or the coating film laminated on the substrate.

14. The method for manufacturing a piezoelectric film-equipped laminated substrate according to claim 9, wherein the first atmosphere and the second atmosphere are controlled to have a relative humidity of 40% or less.

15. The method for manufacturing a piezoelectric film-coated laminated substrate according to claim 14, wherein the first atmosphere and the second atmosphere are controlled to have a relative humidity of 20% or less.

16. The method for manufacturing a laminated substrate with a piezoelectric film according to claim 1 or 9, wherein the transport unit is at least one of a robot arm capable of gripping a substrate, a belt conveyor, an AGV (Auto Guided Vehicle), or an AMR (Autonomous Mobile Robot).

17. Piezoelectric constant d of the piezoelectric film ３３ A method for manufacturing a piezoelectric film-coated laminated substrate according to claim 1 or claim 9, wherein the ratio is 50 pC / N or more.

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